This study presents the pattern of occurrence of sub-Antarctic fur seals (SAFS),
Arctocephalus tropicalis
, in the southern Brazilian coast and evaluate its association with climatic variability and ...anomalies in the concentration of chlorophytes and sea surface temperature in the reproductive colonies of Gough and Tristan da Cunha Islands. Date, sex, and age class of 254 stranded SAFS recorded between 1992 and 2013 were analyzed. Representative indexes of the patterns of climatic variability and environmental variables were obtained between four and five months before the records, the assumed interval of displacement for species between their closest breeding colonies and the southern Brazilian coast. The species was observed in southern Brazil between May and November each year, and most individuals were adult males. The records of SAFS on the southern Brazilian coast were associated with low concentration of chlorophytes interacting with negative sea surface temperature anomalies, and positive events of South Annular Mode, South Atlantic Ocean Dipole and Indian Ocean Dipole. Climatic variability is influencing the ecology SAFS, because it affects the environmental factors, that act as a driver of dispersion of the species. These variables had been interacting together in the region of the breeding colonies, and possibly during the fur seals’ journey towards the Brazilian coast. Considering the current scenario of global climate change, we expect that SAFS will continue to disperse to areas beyond their regular distribution, not only in the direction of the coasts of southern continents, but also further south, towards higher latitudes.
Anthropogenic disturbance is a major cause of the biodiversity crisis. Nevertheless, the role of anthropogenic substrate vibrations in disrupting animal behavior is poorly understood. Amphibians ...comprise the terrestrial vertebrates most sensitive to vibrations, and since communication is crucial to their survival and reproduction, they are a suitable model for investigating this timely subject. Playback tests were used to assess the effects of substrate vibrations produced by two sources of anthropogenic activity- road traffic and wind turbines- on the calling activity of a naïve population of terrestrial toads. In their natural habitat, a buried tactile sound transducer was used to emit simulated traffic and wind turbine vibrations, and changes in the toads' acoustic responses were analyzed by measuring parameters important for reproductive success: call rate, call duration and dominant frequency. Our results showed a significant call rate reduction by males of Alytes obstetricans in response to both seismic sources, whereas other parameters remained stable. Since females of several species prefer males with higher call rates, our results suggest that anthropogenically derived substrate-borne vibrations could reduce individual reproductive success. Our study demonstrates a clear negative effect of anthropogenic vibrations on anuran communication, and the urgent need for further investigation in this area.
In the last decades, an increasing fishing effort and a decreasing trend in fish catches have been observed in southern Brazil. Considering that marine mammals and fisheries usually compete for the ...same resources, it is reasonable to presume that the feeding ecology of these predators is affected by the current scenario. To evaluate this hypothesis, long-term variation in the diet of the South American sea lion (
Otaria flavescens
) relative to fisheries exploitation was analyzed for two periods (1993–2003 versus 2004–2014). The degree of overlap between the relative biomass of the sea lions’ diet and the target species of six types of local fishery was analyzed. An increase in prey overlap between sea lions and fisheries was observed in the more recent sampling period, along with an increase in prey diversity, richness, and niche breadth of the sea lions’ diet. These results suggest that the overfishing scenario could partly explain the modified feeding ecology of the sea lions. In this context, we recommend a review and better regulation of the current fishing effort in the region, which we believe will be an important step to maintain the fish stocks and minimize the impact of fishing on marine top predators.
The South American and cis-andean lizard genus Tropidurus has a complex taxonomic history. Most species were recently described and previous revisions included few specimens from the southern part of ...the continent. Tropidurus torquatus has the broadest geographic distribution in the genus and several morphological and ecological differences were described within its distribution. We analyzed the geographic variation in external morphological characters of Tropidurus torquatus, including large number of samples from southern Brazil. Tropidurus catalanensis is revalidated and Tropidurus imbituba sp. nov., with a restrict distribution in the southern coast of Brazil, is described. The new species is distinguished from Tropidurus catalanensis by the number of dorsal scales. It can be distinguished from T. catalanensis and T. torquatus by a distinct orange ventral coloration in adults, which can reach the lateral portion of the body in adult males. Our analysis also suggests that at least two other undescribed species could be recognized under the name Tropidurus torquatus in southeastern and central Brazil.
Nuptial pads are patches of thickened skin, associated with sexually dimorphic skin glands, present only in the thumbs and fingers of male anurans, and hence considered dimorphic sexual characters. ...Despite the morphological description for many species, the evolution and function of nuptial pads are still unclear. In this study, we describe the presence of nuptial-pad–like structures in females of two species of Melanophryniscus and compare their morphology and histology to males' nuptial pads. The epidermal modifications found in females are conical papillary epidermal projections, similar to the structures found in males; however, the density of these projections in males is twice the average found in females. Also, the nuptial-pad–like structure found in females cannot be considered an actual nuptial pad, because there are no specialized skin glands associated with the structure. This study brings the first records of epidermal modification in females of Melanophryniscus and provides the description of male nuptial pads for the genus.
The geographic distribution of a species is limited by many factors, including its ecological and evolutionary history. Species distribution modeling has been used to evaluate the effects of climate ...and other variables on geographic distribution and to measure the degree of niche similarity among co-occurring species. Our goal in this study was to compare the geographic distributions and ecological niches of four closely related species of lined ground snakes, Lygophis dilepis, L. flavifrenatus, L. meridionalis, and L. paucidens. These species are distributed along the South American Dry Diagonal. We found that the four species of Lygophis overlap somewhat along their distributions with a low degree of niche overlap. Lygophis dilepis shows a disjunct distribution with two isolated populations. The break in the distribution of L. dilepis in Central Brazil is filled by L. meridionalis, which is found mostly in the highlands of the Central Plateau. Because of the disjunct distribution of L. dilepis, we performed species distribution modeling on both populations separately. The environmental niches of the two populations of L. dilepis were indistinguishable according to the niche equivalence tests, but the distribution of one of these populations did not predict the distribution of the second one, and vice versa. Our study shows that niche partitioning may allow for the coexistence of Lygophis species.
(admirable red-belly toad) is a microendemic and critically endangered species found exclusively along 700 m of the Forqueta River, in a fragment of the Atlantic Forest of southern Brazil. One of the ...greatest concerns regarding the conservation of this species is the extensive use of pesticides in areas surrounding their natural habitat. In recent years, the adaptation and persistence of animal species in human-impacted environments have been associated with microbiota. Therefore, the present study aimed to characterize the oral bacterial community of wild
and to address the question of how this community might contribute to this toad's adaptation in the anthropogenic environment as well as its general metabolic capabilities. A total of 11 oral samples collected from wild
were characterized and analyzed via high-throughput sequencing. Fragments of the
variable region 4 (V4) were amplified, and sequencing was conducted using an Ion Personal Genome Machine (PGM) System with 316 chips. A total of 181,350 sequences were obtained, resulting in 16 phyla, 34 classes, 39 orders, and 77 families. Proteobacteria dominated (53%) the oral microbiota of toads, followed by Firmicutes (18%), Bacteroidetes (17%), and Actinobacteria (5%). No significant differences in microbial community profile from among the samples were reported, which suggests that the low dietary diversity observed in this population may directly influence the bacterial composition. Inferences of microbiome function were performed using PICRUSt2 software. Important pathways (e.g., xenobiotic degradation pathways for pesticides and aromatic phenolic compounds) were detected, which suggests that the bacterial communities may serve important roles in
health and survival in the anthropogenic environment. Overall, our results have important implications for the conservation and management of this microendemic and critically endangered species.
ABSTRACT It is generally assumed that lizards are active whenever climatic conditions are favorable. Homonota uruguayensis (Vaz-Ferreira & Sierra de Soriano, 1961) is the only native gecko - and ...nocturnal lizard - living in the northern Pampa biome, and its ecology is poorly known. This study aimed at describing this species’ pattern of daily and annual activity and its relation with environmental temperatures. The study was conducted in the extreme south of Brazil (Rosário do Sul, State of Rio Grande do Sul), between May 2010 and January 2011 at a rocky outcrop located in the Pampa biome. The study was carried out in a total of four seasonal field trips, totalizing 1185 hours of field work. The data were collected, both during the day and the night in 6-hour shifts (duration of the sampling period). The area was randomly covered at each shift to record activity and microhabitat use by the lizards. In total 1541 specimens were recorded throughout the study. Homonota uruguayensis showed diurnal and nocturnal activity in the four seasons, with periods of daily activity varying significantly between all seasons in a cyclic and multimodal pattern, with no significant relation with environmental temperatures. There was no difference in activity related to sex and age classes. Most active lizards were found when air temperatures ranged from 14 °C to 32.9 °C (82% of active lizards) and substrate temperatures ranged from 10 °C to 32.9 °C (87% of active lizards).
RESUMEN La suposición general ha sido que los lagartos son activos cuando las condiciones climáticas son favorables. Homonota uruguayensis (Vaz-Ferreira & Sierra de Soriano, 1961) es la única lagartija nativa - y la lagartija nocturna - que vive en el norte de bioma Pampa. La ecología de esta especie es poco conocida y este estudio tuvo como objetivo describir su patrón de actividad diaria y anual y su relación con las temperaturas ambientales. El estudio se llevó a cabo en el extremo sur de Brasil (Rosário do Sul, Rio Grande do Sul), a partir de mayo 2010 - enero 2011, en un afloramiento rocoso situado en el bioma Pampa. El estudio totalizó cuatro excursiones de campo estacionales y 1185 horas. Los datos fueron recogidos a lo largo de los turnos de 6 horas durante el día y la noche. El área fue recorrida aleatoriamente en cada turno siempre registrandose la actividad y el microhabitat utilizado por los lagartos. A lo largo del estudio, 1541 especímenes se registraron. Homonota uruguayensis presentó hábito diurno y nocturno en las cuatro estaciones, con períodos de actividad diaria variando significativamente entre todas las estaciones en forma cíclica y multimodal, no se observó relación significativa con las temperaturas ambientales. No fue constatada diferencia entre los sexos con relación a la actividad y las clases de edad. La mayoría de los lagartos activos fue encontrada a temperaturas del aire que variaron de 14 °C a 32,9 °C (82% de lagartos activos) y a temperaturas del sustrato entre 10 °C y 32,9 °C (87% de lagartos activos).
We conducted 44 roadside surveys on grasslands landscapes of southern Brazil and Uruguay to study temporal changes in raptor abundance. Each route was surveyed twice in fall/winter and twice in ...spring/summer. Raptor abundance was higher during summer than winter, but did not differ between years. Thirteen of the 33 species recorded showed temporal changes in abundance, or are known to be migrants in the region. White-tailed Kite (Elanus leucurus), Yellow-headed Caracara (Milvago chimachima) and Southern Caracara (Caracara plancus) had higher abundance during fall/winter than spring/summer, which might be attributed to nomadic movements in agricultural landscapes. Changes in abundance of Savanna Hawk (Buteogallus meridionalis) and American Kestrel (Falco sparverius) suggest irruptive or nomadic movements. Turkey Vulture (Cathartes aura), Snail Kite (Rostrhamus sociabilis) and White-tailed Hawk (Geranoaetus albicaudatus) were more abundant in spring/summer than fall/winter, and our results suggest that they are partial migrants in the region. Variations in temperature, water level, and land use in agro-environment as well as dispersion, recruitment, and ephemeral concentration of food resources probably are the causes of fluctuation observed. Our results provide a starting point to better understand raptor temporal fluctuations and abundance in southeastern South America, but further investigations are required. Realizamos 44 censos a lo largo de caminos ubicados en paisajes de pastizales del sur de Brasil y Uruguay para estudiar los cambios temporales en las abundancias de rapaces. Cada ruta fue censada dos veces en otoño/invierno y dos veces en primavera/verano. La abundancia de rapaces fue mayor durante el verano que en el invierno, pero no difirió entre años. Trece de las 33 especies registradas evidenciaron cambios temporales en sus abundancias, o es sabido que son migrantes en la región. Elanus leucurus, Milvago chimachima y Caracara plancus tuvieron una mayor abundancia durante otoño/invierno que en primavera/verano, lo que puede ser atribuido a movimientos nómades en los paisajes agrícolas. Los cambios en la abundancia de Buteogallus meridionalis y Falco sparverius sugieren movimientos nómades o de irrupción. Cathartes aura, Rostrhamus sociabilis y Geranoaetus albicaudatus fueron más abundantes en primavera/verano que en otoño/invierno y nuestros resultados sugieren que son migrantes parciales en la región. Las variaciones en la temperatura, el nivel del agua y el uso del suelo en ambientes agrícolas, así como también la dispersión, el reclutamiento y la concentración transitoria de fuentes de alimento son probablemente las causas de la fluctuación observada. Nuestros resultados proporcionan un punto de partida para entender mejor las fluctuaciones temporales de las rapaces y sus abundancias en el sureste de América del Sur; sin embargo, se requieren mayores investigaciones.
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